One of the really intriguing aspects of the blogOspheric chatterfest is how the big markets tend to react to rumors from key business related blogs. When TechCrunch reported yesterday that talks between Microsoft and Yahoo had resumed Yahoo stock increased, only to fall after several other blogs reported the rumors as false or weak.

Although I have no reason to believe that Mike Arrington or Henry Blodget are trading options based on their market-moving blog reporting, I’m not at all clear it would be illegal for them to do so as long as they were reporting “real” rumors.

Henry answered at his blog that posting a false rumor to manipulate for investment purposes would likely be seen by SEC as a violation but this leaves a lot of gray areas open for an aggressive options trader/journalist.

Here’s what I just asked Mike Arrington over at TechCrunch:Mike just to set the record straight the ValleyWag poster “Mike Arrington”, who claims to have made 10k trading on Yahoo rumors, is fake … right?

More importantly I’m very interested in your views on legality/ethics of trading Yahoo options based on the rumor mill. Let’s say you heard a solid rumor that MS was about to offer $37 for Yahoo and Yahoo was going to sell. Could you legally trade on that before you posted it? One second after?

What if you emailed *me* right before you posted, I think I could legally trade based on current SEC rules, right?

P.S. What kind of Single Malt Scotch do you like? : )

Although I have no plans to manipulate any markets, it is reasonable to assume that if a market can be legally manipulated it *will be* manipulated, and soon.